Cosine question

1. The problem statement, all variables and given/known data
While solving the integral of a wave function,I came across the term cos(n*pi) , where n is an integer. Is that term equal to +1 or -1 (I know that it could be either one depending on whether n is odd or even) but how do I proceed with the integral?

OK, so you're trying to integrate and you have somewhere a factor of [itex]\cos(n\pi)[/itex], where [itex]n[/itex] is an integer. Is that right? In that case you can just replace [itex]\cos(n\pi)[/itex] with [itex]\pm 1[/itex].

This looks pretty straightforward to me. It might help me understand why this is giving you trouble if you typed out the integral that you are trying to do, what you have done, and where you got stuck.